1. Field of the Invention
The present invention relates to discriminating orientation of an input image.
2. Related Background Art
In recent years, document digitizing devices like character recognition devices or facsimile apparatuses have been developed to be in a realization as computer technology has higher performance. With the wide spread of these devices, principally in business applications, demand has been growing for converting vast amounts of documents to image data at a time with a scanner having an auto document feeder (ADF). For that purpose, efficiency is attracting the most attention from industry.
Typically, ADFs are fed with numerous documents of the same size and orientation. If documents in longitudinal direction and lateral direction are mixed, obtained image data will have different orientations. If some documents have different sizes, such documents may tend to rotate in travelling in an ADF and obtained image data will be more likely to have a wrong orientation.
Since a conventional character recognition device or a filing device assumes that documents is processed in a common orientation, an operator arranges their orientations to be in a common orientation before the documents are fed into such a device. Moreover, in order to ensure proper operations, after documents have been processed by a device, an operator must visually inspect all document images on a display one after another and if they have wrong orientations, the operator must provide an instruction to arrange it by an appropriate angle (90°, 180° or 270°) accordingly. Therefore, processing vast amounts of documents at a time may significantly degrade practicability of the devices in the point of light efficiency and burden to operators.